which also leave invariant the solutions constructed according
to (REF ), as we will see.
Alternatively, (REF ) can be used
to set up a new solution out of a given solution.
For comparison purposes, we write the Khare-Sukhatme notation [1]}, [2]}
for the parameters \(\mathbf {l}\) , \(\mathbf {m}\)  and \(k^2\) , namely,
\(\mathbf {l}= b,\qquad \mathbf {m}=a, \qquad k^2=m:\qquad \mbox{Khare-Sukhatme \cite {khare,khare2}}.\) 
